Dissipative Landau-Zener tunneling: crossover from weak to strong environment coupling

• Main Authors: Dai, X, Trappen, R, Chen, H, Melanson, D, Yurtalan, M. A, Tennant, D. M, Martinez, A. J, Tang, Y, Mozgunov, E, Gibson, J, Grover, J. A, Disseler, S. M, Basham, J. I, Novikov, S, Das, R, Melville, A. J, Niedzielski, B. M, Hirjibehedin, C. F, Serniak, K, Weber, S. J, Yoder, J. L, Oliver, W. D, Zick, K. M, Lidar, D. A, Lupascu, A
• Format: Journal Article
• Language: English
• Published: 05-07-2022
• Subjects: Physics - Quantum Physics
• DOI: 10.48550/arxiv.2207.02017

Landau-Zener (LZ) tunneling, describing transitions in a two-level system
during a sweep through an anti-crossing, is a model applicable to a wide range
of physical phenomena, such as atomic collisions, chemical reactions, and
molecular magnets, and has been extensively studied theoretically and
experimentally. Dissipation due to coupling between the system and environment
is an important factor in determining the transition rates. Here we report
experimental results on the dissipative LZ transition. Using a tunable
superconducting flux qubit, we observe for the first time the crossover from
weak to strong coupling to the environment. The weak coupling limit corresponds
to small system-environment coupling and leads to environment-induced
thermalization. In the strong coupling limit, environmental excitations dress
the system and transitions occur between the dressed states. Our results
confirm previous theoretical studies of dissipative LZ tunneling in the weak
and strong coupling limits. Our results for the intermediate regime are novel
and could stimulate further theoretical development of open system dynamics.
This work provides insight into the role of open system effects on quantum
annealing, which employs quantum tunneling to search for low-energy solutions
to hard computational problems.